The present invention relates to a device having two different porous surfaces attached directly or indirectly to one another and a method for forming the same.
The present application is particularly directed toward a method of forming porous or partially-porous metallic structures having different porosities for bone ingrowth and soft tissue ingrowth or attachment.
One method of producing the different porous structures uses rapid prototyping to produce low density three-dimensional structures. This is useful in applications where porous and partially-porous metallic structures, and more particularly metal porous structures with interconnective porosity are advantageous for use. In addition, composite structures of metal and porous ceramics or porous polymer can be used.
Many structures, especially in the medical arts, require two different surfaces, each adapted for their own purposes. Along this line, a structure may have a first surface which needs to be porous for tissue in-growth and a second surface which could be adapted to be a bearing surface. See for example U.S. Patent Publication No. 2007/0142914, the disclosure of which is incorporated herein by reference. Further, the first surface or portion may include different layers having different gradients of porosity. For example, the first surface may include an outer region having a porosity of approximately 80%. As you move normal with regard to the first surface the porosity may alter such that the porosity is increased or in a preferred embodiment, the porosity decreases even until the porosity is almost zero. Of course, the present invention contemplates a situation where the porosity changes from position to position depending on the requirements of the device.